This invention relates to a telescoping shock absorber which finds particular use in motor vehicles and which is of the type that has a cylinder and a reciprocating piston accommodated in the cylinder. The piston is provided with separate flow channels for the two possible flow directions of a damping medium and valves in the channels for ensuring a unidirectional flow in each channel.
There are also known telescoping shock absorbers in which a sole channel in the piston is utilized for accommodating the damping medium which alternatingly flows therein in both directions. The telescoping shock absorber having two separate channels for the two flow directions has the advantage, however, that for each displacement of the piston, the damping medium situated in the zone of the channel valves is driven out, together with any gas bubbles that may have been formed. Such gas bubbles, as it is known, may, particularly if they are located in the valve zone, alter the damping characteristics of the shock absorber in an undesirable manner. On the other hand, however, in telescoping shock absorbers having separate channels for the two flow directions, difficulties may be encountered if the channels are designed for achieving predetermined shock absorbing characteristics. As a function of the mass of the movable valve member and the design of the associated valve springs, upon reversal of the piston motion a hysteresis is introduced so that irregularities are superimposed on the desired course of the damping curve which expediently should depend solely from speed.